Portion of a display screen with a user interface



THE FIGURE is a front view of a user interface for a portion of a display screen showing the claimed design.

The portions of the user interface illustrated in broken lines form no part of the claimed design. The outer edge of the portion of the display screen is understood to be congruent with the outer edge of the user interface. 

The ornamental design for a portion of a display screen with a user interface, as shown and described. 